Rail-joint-testing apparatus.



No. 645,384. Patented Mar. l3, I900.

n. w. comma RAfLJomT TESTING APPARATUS. (Application filed Nov. 1a,1899.\ (No Model.) I 2 Sheets-Sheet 1..

\/\//T 55555. v M x VENTUR; $2M @J No. 645,384. Patented Mar. l3, I900;

R. w CONANT. RAIL JOINT TESTING APPARATUS (Applies Hon filed Nov 13,1899.1

2 Sheets-Sheet 2,

(No Model.)

UNITED STATES I PATENT met.

ROGER W. CONANT, OF BOSTON, MASSACHUSETTS.

RAlL-JOlNT-TESTING APPARATUS.

SPECIFICATION forming part of Letters Patent No. 645,384, dated Matt 13,1906. Application filed November 13, 1899- Serial No. 736,747. (Nomodel.)

To all whont it may concern Be it known that I, ROGER W. CONANT, acitizen of the United States, residing in Boston, in the county ofSuffolk and State of Massachusetts, have invented an Improvement inRail-Joint-Testing Apparatus, of which the following description, inconnection with the accompanying drawings, is a specification, likeletters and figures on the drawings representing like parts.

This invention relates to an apparatus for rapidly and efficientlymeasuring electrical resistances, and especially very low resistances,such as the resistance of rail-joints in the tracks of electric-railwaysystems.

In accordance with this invention I employ three portablecircuit-terminals, two of which are adapted to make contact with theconductor to be measured and the other of which is adapted to beconnected with a known or computable resistance in circuit with theunknown resistance. The intermediate or central portablecircuit-terminal is connected in circuit with the other twocircuit-terminals through a telephone-receiver, so that thelineincluding said telephone forms part of two distinct metalliccircuits,whereby sounds produced at the telephone by the making orbreaking of one circuit may be compared with the sounds produced by themaking or breaking of the other circuit and whereby said sounds may bebalanced or rendered substantially the same by changing one of theoutside circuit-terminals with relation to the circuitterminal connectedwith the telephone. In this manner a comparative means is provided formeasuring the resistance included in one circuit between the centralterminal and one of the outside terminals. cuit may and preferably willinclude in it a circuit-interru pter, preferably a break-wheel operatedby a clock mechanism, and said telephone and circuit-interrupter may becarried by a suitable box or case, which, preferably, also contains acoil and a resistance connected in shunt-circuit with the telephone,which shunt-circuit is controlled by a switch located on the outside ofthe box or case of the instrument. Thetwo independent or distinctcircuits are adapted to be controlled by a switch or circuit-controllercarried by the box or case and readily accessible, so that it may bethrown or moved substantially in an in- The telephone-cin stant toinclude the telephone first in one and then in the other of saidcircuits to make the comparison of sounds desired, and which switch orcircuit-controller in its normal or central position connects thetelephone with both circuits, so that if the resistance included betweenthe central portable terminal and one outside terminal is equal to theresistance be tween the central terminal and the other outside terminalthen the telephone will remain silent upon interruption of its circuit.

The invention, as above described, is particularly well adapted formeasuring low resistances, such as the rail-joints of the tracks ofelectric railways, without the use of current other than that derivedfrom the track and employed in the car-service, the resistance of therail-joint being made known by the length of the rail between thecentral portable terminal and the outside terminal on the same side ofthe joint being measured.

These and other features of this invention will be pointed out in theclaims at the end of this specification.

Figure 1 is a perspective view of a box or case forming part of anapparatus embodying this invention Fig. 2, a front elevation of the boxor case shown in Fig. 1 with its cover raised and its front sidepartially broken away; Fig. 3, a plan view of the box or case with itscover removed; Fig. 4, an elevation of one of the portablecircuit-terminals adapted to make contact with the rail and to beconnected with the box or case shown in Fig. 1; Fig. 5, a diagram ofcircuits, to be referred to, which illustrates the operation of theillvention.

In the present instance I have shown what I regard as the most efficientform of apparatus for effecting the object desired. Referring to Fig. 1,a represents a box or case provided with a cover I) and with a strap 0,which is adapted to be passed over the shoulders of the operator,thereby leaving both hands of the operator free to work the apparatus.The cover b is provided on its upper face with two terminal plates d 6,having their ends substantially close together and adapted to be bridgedor connected by a movable switch-lever f, which is also capable ofmaking contact separately with either of the terminals d e. The cover I)also has pivoted to it a switch-lever 9, adapted to cooperate with aseries of terminals or buttons h, for a purpose as will be described.The box or case a on its front side has connected to it threebinding-posts 2' 7' 7t and has pivoted to it on the same side a lever m,adapted to make contact with a circuit terminal or button it. The box orcase a on one end (see Fig. 3) is provided with binding-posts p, withwhich are adapted to be connected wires 1 7", leading to atelephone-receiver s of any suitable or usual construction. The box orcase at its opposite end, as shown in the present in stance, is providedwith a lever 15, adapted to cooperate with the terminal u. The box orcase, as shown in Fig. 3, is subdivided by partition-walls 2 3 4 intocompartments 5, 6, 7, and 8, the walls 2 4 being preferably maderemovable and the compartments 5 8 being designed and adapted to containduplicate circuit-breakers, only one of which is shown and which may andpreferably will consist of a break-wheel 9, operated by a clockmechanism 10 of any suitable or usual construction, and with whichcooperates a contact-spring or terminal pen 12, mounted on aninsulatingblock 13, fast to the framework of the clock 10, the clockmechanism being suitably attached to the partition-wall 4, so as to beremoved therewith for repairs or other purpose and preferably bearingagainst sound-damping material interposed between said clock andpartition. The clock mechanism 10 is adapted to be wound by a suitablekey 14, extended through a suitable hole in the front side'of the case,and the break-wheel is adapted to be held at rest by means ofaspring-arm 15, fastened to the inner side of the box or case andnormally engaging the shaft or pivot of the escapementfan 16. Thespring-arm has extended through it the pivot 17 for the lever mand isadapted to be disengaged from the pivot or shaft of the escapement-fan16 when the lever m is thrown into engagement with the terminal n, whichlatter forces the lever m outward and draws the spring-arm 15 away fromthe escapement-shaft, the button or terminal 11 acting in this case likea cam. The terminal pen or brush 12 in the present instance is includedin circuit with the telephone 8, and the switch m is likewise includedin the said circuit, the terminal pen or brush being connected with thecentral binding-post j by the wire 20. The spring-arm 15 is connectedbywire 19 with the clock-frame. The outside binding-posts 7t 2' areconnected within the box by wires 21 22 (see Fig. 5) to the terminals 61c, and the lever f is connected bywires 24 25 with the binding-post p,and the wire 24 is connected by wire 26 to the switch-lever g,cooperating with the terminals h, to which is connected the resistance27, and also cooperating with a blank terminal or button to, one of theterminals It being connected by wire 28 to a coil 29, which is connectedby wire 30 to the wire 31, connected with the binding-post o, the wire31 being joined by Wires 32 33 to the terminal n. The bindingposts t'j7c are adapted to have connected to them the flexible conductors 4O 4142, connected with portable circuit-terminals, three in number andmarked 43 44 45 in Fig. 5. The circuit-terminals are and may be of likeconstruction and preferably the same as that shown in Fig. 4, the sameconsisting of an edgetool 46, adjustably secured, as by a set-screw 47,in a metal holder 48, provided with a handle 49, of wood or othersuitable material, which is preferably provided,as herein shown, with agroove 50, in which the conductor is laid.

In Fig. 5 I have shown two rails 51, making the joint 52, the resistanceof which it is desired to test. For this purpose the box or case a andone portable circuit-terminal, as 43, are carried by the operator makingthe test, while the other portable circuit-terminals 44 45 are carriedby an assistant.

In operation the assistant places the terminals 44 45 in contact withthe rails 50 51 on equal sides of the joint 52, and when thus placed theoperator carrying the box moves the switch-lever f onto the terminal 01and then sets the circuit-breaker in operation by moving the lever montothe terminal-button n and, preferably, also moves the switch-lever gonto the first terminal It, so as to include the coil 29, which I preferto designate as the kicking-coil, the office of which is to intensifythe sound at the telephones, which sound is produced in the presentinstance by the break in the telephone-circuit. The circuit through thetelephone may be traced as follows: from the portable terminal 45 tobinding-post by wire 42, thence by wire 21, terminal (1, switch f, wires24 25 r to telephone s, thence by wires q 31 32 33 to switch- '1ever m,wire 19 to break-wheel 9, thence by pen 12, wire 20 to binding-post j,and thence by Wire 41 and terminal 44 to rail 50. Having obtained thesound given by interrupting the circuit, including the rail-joint, theoperator brings the portable terminal 43 into engagement with the rail50 and throws the leverf over onto the terminal 6, and the break-wheel'9 continuing to run will give a sound at the telephone varying intensity, according to the length of the rail 50 between the terminals 4344, and by moving the terminal 43 toward or from the terminal 44, so asto vary the length of the rail included in the telephone-circuit, thesound at the telephone is made equal to or substantially equal to thesound produced when the rail-joint is in circuit with the telephone. Thecircuit through the telephone, including the terminal 43, may be tracedas follows: from the terminal 43 by wire 40 to binding-post 1', thenceby wire 22, terminal e, switch-lever f, wires 24 25 'r through thetelephone 5, thence-by wires q 31 32 33, lever 'm,

wire 19, break-wheel 9, pen 12, wire 20 to binding-postj, and thence bywire 41,terminal 44, and rail 50 to terminal 43. It will thus be seenthat by moving the lever f first onto the terminal 0 and then onto theterminal 6 the sounds may be quickly compared, so that by moving theterminal 43 along the rail 50 the said sounds may be renderedsubstantially equal or balanced, and when this point has been reached itmay be tested by moving the switch fto its central position and so as toconnect the terminals cl e together, in which position if the resistanceof the rail between the terminals 43 44 equals the resistance of therail-joint the telephone will remain silent when its circuit is broken.The resistance of the track per foot in length is known, and theresistance of the joint is made known by the length of the rail betweenthe terminals 43 44.

I prefer to use the kicking-coil 29; but an induction-coil may be usedin place thereof, or the kicking-coil could be omitted when alow-resistance telephone-receiver is used. The kicking-coil ispreferred, as it concentrates the available energy on the break in thetelephone-circuit and practically no sound is obtained on the make,thereby increasing the sensitiveness of the instrument.

The resistance 27 is preferred, as it maybe used to regulate or diminishthe sound on strong track-currents.

The apparatus herein described is especially efficient in measuring verylow resistances.

I have herein described one use to which the apparatus is particularlywell adapted; but I do not desire to limit my invention in this respect,as it may be used to measure other resistances than those specified.

I prefer to employ the break-wheel and motor mechanism therefor and theswitch f; but I do not desire to limit my invention in this respect, asthey may be omitted and sounds produced in the two circuits by liftingthe terminals 43 45 from the conductors with which they are engaged andthe silent test obtained by lifting the central terminal.

In the diagram Fig. 5 I have shown a duplicate break-wheel and motormechanism which in practice may be secured to the partition-wall 2 andlocated in the compartment 5, so that in case of accident to the motormechanism for the break-wheel in compartment 8 the duplicate apparatusin compartment 5 may be used at once, thereby avoiding delays in thework.

In practice the resistance of the wires between the terminal 43 andswitch-terminal e should be made equal to the resistance of the wirebetween terminal 45 and switch-terminal d.

By the term kicking-coil I mean a selfinductive coil.

I claim- 1. In an apparatus of the character described, the combinationwith two independent metallic circuits having a conductor common toboth, and a telephone-receiver in the common conductor, substantially asand for the purpose specified.

2. In an apparatus of the character described, the combination with twoindependent metallic circuits having a conductor oommon to both, atelephone-receiver and a circuit-interrupter in the common conductor,substantially as described.

3. In an apparatus of the character described, the combination with twoindependent metallic circuits having a conductor common to both, atelephone-receiver and a circuit-interrupter in the common conductor,and a switch in circuit with said telephone cooperating with both ofsaid independent circuits, substantially as described.

4. In an apparatus of the character described, the combination with twoindependent circuits having a conductor common to both, atelephone-receiver in the common conductor, a shunt-circuit for saidtelephone provided with a kicking-coil, substantially as described.

5. In an apparatus of the character described, the combination with twoindependent circuits having a conductor common to both, atelephonereceiver in the common conductor, a shunt-circuit for saidtelephone provided With kicking-coil, and with a resistance, and aswitch in said shunt controlling said resistance.

6. In an apparatus of the character described, the combination with twoindependent circuits having a conductor common to both, atelephone-receiver in said common conductor, abreak-Wheel in said commonconductor, and a motor mechanism to operate said break-wheel, and meansto control the said motor mechanism, substantially as and for thepurpose specified.

'7. An apparatus for measuring electrical resistances by a comparison ofsounds produced in a circuit including the resistance to be measuredwith sounds produced in a circuit including a known resistance, itcomprising movable terminals adapted to make contact with the resistanceto be measured, conductors connected to said terminals, a tele phoneconnected to one of said conductors, a third movable terminal adapted tobe connected with a known resistance and connected with the conductor towhich the telephone is connected, the said third movable terminal beingmovable toward and away from the terminal for the telephone,substantially as described.

8. In an apparatus of the character described, the combination with atelephone-receiver, a circuit-breaker in the telephone-circuit, ashunt-circuit for said telephone between the telephone and saidcircuit-breaker, and a kicking-coil in said shunt to intensify the soundat the telephone, substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribin g witnesses.

ROGER W. OONANT.

Witnesses:

JAs. H. CHURCHILL, J. MURPHY.

